1. Field of the Invention
The present invention relates to treating eyes, and more particularly to devices and methods for forming an adaptive optic in the capsule of a human eye.
2. Description of Related Art
Referring to FIGS. 1A and 1B, the zonule of Zinn (Zinn's membrane, ciliary zonule) is a ring of fibrous strands 52 connecting the ciliary body with the crystalline lens 54 of the eye. The zonule of Zinn is split into two layers: a thin layer which lines the hyaloid fossa and a thicker layer which is a collection of zonular fibers. Collectively, the fibers are known as the suspensory ligament of the lens. The action of the suspensory ligament is to place tension on the capsule 56 (shown in partial section view) of the lens 54 to keep it centered on the eye. While the suspensory ligament accommodates the optics of the eye by changing the magnitude of tension on the capsule, the capsule is nevertheless in tension through all accommodative states of a normal eye. Correspondingly, when an intraocular lens (IOL) is placed in the eye it is not bonded to the capsule and hence is not in tension. Currently the only means for centering an IOL implanted within the capsule is to provide structure which creates forces between the IOL and the capsule to center the IOL. This is accomplished with haptics, small loop shaped springs on the equator of the lens, which apply a compressive force along the equator of the lens. The net effect is to increase the tension placed on the capsule at the equator, rendering ineffective any changes in the ciliary muscle fibers which otherwise would change the shape of a material lens to provide accommodation and alter the power of the lens. In the normal lens, as the ciliary muscles contract (like a sphincter) the zonules relax and the lens becomes rounder to provide accommodation and variable power. Today's flat IOLs need haptics to keep the IOL in place. The haptics do not maintain the natural shape of the capsular bag. The zonular fibers surrounding the capsule are thus relaxed beyond the normal range of contraction of the ciliary muscle. Thus the ciliary muscle cannot relax the zonular fibers more, and the capsular bag remains in a position of over accommodation. Thus, physiological accommodation is not possible with any type of thin and flat IOL. It is a further object of the present invention to provide an IOL with an approximately ellipsoidal profile.
This release of tension of the zonular fibers causes the lens to become more spherical, thereby increasing the power of the lens to focus on near objects.
Referring again to FIGS. 1A and 1B, to understand the sensitivity of the accommodative function, it is important to recognize there are both radial 62 and anterior-posterior (AP) zonular fibers (64 and 66). According to the Schachar hypothesis when the ciliary muscle contracts, AP zonular tension is increased (the angle between 64 and 66 increases) while radial zonular fiber tension decreases. The increase in AP zonular tension occurs peri-circumferentially causing the central surfaces of the crystalline lens 54 to steepen, the central thickness of the lens to increase (increasing the anterior-posterior diameter), and the peripheral surfaces of the lens to flatten. While the tension on AP zonules is increased during accommodation, the radial zonules are simultaneously relaxing.
As a consequence of the changes in lens shape during human in vivo accommodation, the central optical power of the lens increases and spherical aberration of the lens shifts in the negative direction. Because of the increased AP zonular tension on the lens during accommodation, the surface tension of the lens capsule is increased despite the reduction in radial tension and the lens remains stable and unaffected by gravity. To be more specific, the surface tension is actually the interaction between the AP zonular tension and the anterior-posterior connectivity provided by the fibular structure 70 of the lens 54. This is an important feature striking a compromise between low modulus and resistance to distortion by gravity. The same shape changes that occur to the crystalline lens during accommodation are observed when circumferential tension is applied to any encapsulated biconvex object that encloses a minimally compressible material (volume change less than approximately 3%) and has an elliptical profile at the equator of the lens with an aspect ratio ≤0.6 (minor axis/major axis ratio). The fibular structure of the lens is likely responsible for maintaining the aspect ratio below 0.6 of the elliptical profile. Circumferential tension is very efficient when applied to biconvex objects that have a profile with an aspect ratio ≤0.6. Minimal circumferential tension tends to flatten the equator of the lens, slightly increasing the lateral equatorial diameter and causing a large increase in central curvature resulting in a more spherical-shaped lens. Vertebrates that have lenses with aspect ratios ≤0.6 have high amplitudes of accommodation; e.g., primates and falcons, while those vertebrates with lenticular aspect ratios >0.6 have low amplitudes of accommodation; e.g. owls and antelopes.
The decline in the amplitude of accommodation eventually results in the clinical manifestation of presbyopia. It has been widely suggested that the age-related decline in accommodation that leads to presbyopia occurs as a consequence of sclerosis (hardening) of the lens. However, the lens does not become sclerotic until after 40 years of age. In fact, the greatest decline in the amplitude of accommodation occurs during childhood, prior to the time that any change in hardness of the lens has been found. The decline in accommodative amplitude, rapid in childhood and slow thereafter, follows a logarithmic pattern that is similar to that of the increase in the equatorial diameter of the lens, which is the most likely basis for the accommodative loss. As the equatorial diameter of the lens continuously increases over life, baseline ciliary tension simultaneously declines. This results in a reduction in baseline ciliary muscle length that is associated with both lens growth and increasing age. Since the ciliary muscle, like all muscles, has a length-tension relationship, the maximum force the ciliary muscle can apply decreases, as its length shortens with increasing age. This is the etiology of the age-related decline in accommodative amplitude that results in presbyopia. Any implant that increases radial compression internal to the capsule (directed outward), increases the equatorial lens diameter and decreases the amplitude of accommodation.
Thus, an IOL which is responsive to the natural accommodative mechanism of the human eye preferably possesses the following properties:                1. Does not apply a radial force directed outwards near the equatorial plane of the capsule, so as not to work against accommodation.        2. Possesses a centering mechanism largely based on volume of the IOL relative to the volume of the natural capsule        3. Is resistant to gravitationally induced asymmetry, yet is highly compliant        4. Possesses an internal structure that tends to stabilize the shape of the IOL in an ellipse with an aspect ratio approximately <0.6        5. The surface of the IOL follows, without relative motion, changes in shape of the natural capsule        6. Possesses approximately the same modulus or less than the capsule        7. Possesses a fixed index of refraction discontinuity relative to the capsule        8. Possesses approximately the same water content as lens matter        9. Is naturally buoyant (same specific gravity as surrounding tissue)        10. Provides a means to adjust the set point dioptric power during implantation        11. Provides an accommodative dioptric range of 15 Diopters        12. Provides capsule filling lens volume        13. Requires minimal surgical disruption by being formed at the implantation site        14. Has a minimized lens thicknessRequirements 12 and 14 appear to be contradictory, and it is this contradiction that will be addressed presently. The focal length of an implanted IOL can be calculated from        
  ϕ  =            1      f        =                  (                  n          -          1.33                )            ⁡              [                              1                          R              1                                -                      1                          R              2                                +                                                    (                                  n                  -                  1.33                                )                            ⁢              d                                                      nR                1                            ⁢                              R                2                                                    ]            Where                f is the focal length of the lens,        n is the refractive index of the lens material,        R1 is the radius of curvature of the lens surface closest to the light source,        R2 is the radius of curvature of the lens surface farthest from the light source,        d is the thickness of the lens (the distance along the lens axis between the two surface vertices).        Φ is the optical power in diopters if R is in meters.The signs of the lens' radii of curvature indicate whether the corresponding surfaces are convex or concave. The sign convention used to represent this varies, but here if R1 is positive the first surface is convex, and if R1 is negative the surface is concave. The signs are reversed for the back surface of the lens: if R2 is positive the surface is concave, and if R2 is negative the surface is convex. If either radius is infinite, the corresponding surface is flat. With this convention the signs are determined by the shapes of the lens surfaces, and are independent of the direction in which light travels through the lens.Making the simplifying assumption R1=−R2,        
  ϕ  =            1      f        =                  (                  n          -          1.33                )            ⁡              [                              2                          R                              1                ⁢                                                                                                -                                                    (                                  n                  -                  1.33                                )                            ⁢              d                                      nR              1              2                                      ]            Then the second term
            (              n        -        1.33            )        ⁢    d        2    ⁢          nR      1      2      subtracts from the first, reducing the power of the optical system. Decreasing the radius of curvature, making the lens rounder, increases the second term much faster than the first term. The zero power condition, ϕ=0, occurs when
                    2                  R          1                    -                                    (                          n              -              1.33                        )                    ⁢          d                          nR          1          2                      =    0    Or                    2        ⁢                  nR          1                            (                  n          -          1.33                )              =    d  When the lens is a perfect sphere, R is about 4 mm and
      2    ⁢    n        (          n      -      1.33        )  is approximately 8, so d is approximately 8R. Accordingly, it is very important that the IOL not be compressed equatorially. This is perhaps the reason why the natural lens is always in tension with the suspensory ligament. Placing an equatorial ring inside a compliant IOL which is not suspended within the capsule is not preferred because it would almost certainly degrade accommodation range during ciliary contraction or become de-centered during ciliary dilation. An IOL which places an outward radial force on the capsule, a lens configured like the Crystalens, would be predisposed to one or both of these limitations.
It is worth noting that d is 0 if the equator of the lens is not flattened at any point during accommodation (refer back to the definition of d). Suspension readily accomplishes this criterion for any volume of lens capable of fitting within the capsule, whereas a passively inserted bag-like IOL would suffer significant optical power loss if the equatorial perimeter of the IOL were to sag away from the equator of the capsule, or otherwise not be actively suspended by the capsule. Conversely, any inserted ring or bag thickening around the equator to keep the lens in contact with the capsule would resist accommodation, or worse cause the equator to fold under accommodation. One solution is to glue or otherwise attach the bag-lens to the equator of the capsule so that during all phases of accommodation the bag is in tension. This would require the bag to be highly elastic.
It is instructive to consider the specific composition of the natural lens and capsule. Referring to FIG. 1C, the lens capsule 75 is a smooth, transparent basement membrane that completely surrounds the lens. The capsule is elastic and is composed of collagen. It is synthesized by the lens epithelium and its main components are Type IV collagen and sulfated glycosaminoglycans (GAGs). The capsule is very elastic and so causes the lens to assume a more globular shape when not under the tension of the zonular fibers, which connect the lens capsule to the ciliary body. The capsule varies from 2-28 micrometers in thickness, being thickest near the equator 77 and thinnest near the anterior 79 and posterior 80 poles.
Referring now to FIGS. 1A and 1B, the lens fibers 70 form the bulk of the lens 54. They are long, thin, transparent cells, firmly packed, with diameters typically between 4-7 micrometers and lengths of up to 12 mm long. The lens fibers stretch lengthwise from the posterior to the anterior poles and, when cut horizontally, are arranged in concentric layers 80 rather like the layers of an onion. If cut along the equator, it appears as a honeycomb 70. The middle of the fibers is at the equator 60. The middle of each fiber lies in the equatorial plane. These tightly packed layers of lens fibers are referred to as laminae 80. The lens fibers are linked together via gap junctions and interdigitations of the cells that resemble “ball and socket” forms. It is this later feature that enables the fibers to be stretched in the axial direction without sagging in the equatorial plane. Thus, in order to enable a bag-like IOL one prefers the IOL to be filled with a series of elastic rods preferring an extended length, the extended rod lengths chosen such that they are shaped to the radius of curvature achieved at the high power extreme of the accommodative optical power spectrum while each rod in all accommodative states experiences approximately the same magnitude of tension-compression. To achieve this each rod needs to be articulated laterally with its neighboring rods. The rods must be suspended in a fluid, incompressible medium. And the rod ends must be bonded to either the natural capsule or a synthetic tightly fitting bag, such that the shape of the bag is substantially a function of the axial and lateral spring constants of the rods and their lateral pivoting connector. The lateral pivoting connection must be both elastic and pivoting in order to provide for equatorial diameter change that does not overly constrain lens axial lengthening.
Heretofore, a number of patents and publications have disclosed IOL devices and other optical implant devices, the relevant portions of which may be briefly summarized as follows.
U.S. Pat. Nos. 5,213,579 and 5,091,121 describe an intraocular lens including a balloon member formed of an elastomers and adapted to be inserted into a capsular bag of an eye, an optically transparent fluid which is injected into the balloon member so that the balloon member expands and fills the capsular bag, and a tube provided on the balloon member and having a bore through which the optically transparent fluid is injected into the balloon member. The bore of the tube is filled with and closed by a gel filler. The fluid serving as a lens medium is injected into the balloon member through the tube, with the gel filler inhibiting leakage of the fluid from the balloon member.
U.S. Pat. No. 5,391,590 discloses an injectable intraocular lenses. In one embodiment, such injectable compositions comprise polymer mixtures derived from the polymerization, for example, cross-linking, of curable components in precursor mixtures. These precursor mixtures comprise curable component comprising: (A) an unsaturation functional (vinyl group-containing) polyorganosiloxane component, (B) an organosilicon component including silicon-bonded hydride groups which react with the unsaturation functional groups included in (A) during the polymerization, and (C) an effective amount of a platinum group metal-containing catalyst component; and a polymer component which is substantially non-functional.
U.S. Pat. No. 6,613,343 relates to pre-polymerized compositions comprising polysiloxanes suitable for the preparation of accommodating intraocular lenses, having a specific gravity of greater than about 1.0, a refractive index suitable for restoring the refractive power of the natural crystalline lens and a viscosity suitable for injection through a standard cannula.
U.S. Pat. No. 6,361,561 describes polysiloxanes suitable for the preparation of intraocular lenses by a crosslinking reaction, having a specific gravity of greater than about 1.0, a refractive index suitable for restoring the refractive power of the natural crystalline lens and a viscosity suitable for injection through a standard cannula.
U.S. Pat. No. 3,947,401 discloses an intraocular lens assembly for increased depth of focus and has a frame configured to vault posteriorly in an eye and an optic attached thereto. Pressure from ciliary muscle contraction moves the optic anteriorly to focus the eye for near vision. U.S. Pat. No. 3,947,401 discloses a bulk polymerized, water insoluble but water swellable polymer of monomers comprising water soluble monoester of acrylic or methacrylic acid with a polyhydric alcohol; and glycidyl methacrylate, and/or glycidyl acrylate, and/or glycidyl crotonate. The polymer may be swelled in aqueous solution to provide a transparent hydrogel having excellent physical properties, and suitable in an ophthalmic lens.
U.S. Pat. No. 4,050,192 discloses a multifocal ophthalmic lens of homogeneous transparent optical material and method and apparatus for forming same, useful for the correction of the refractive error and the accommodative insufficiency or absence of accommodation in presbyopia and in aphakia, the lens characterized by having a unique variable front surface and a coacting spherical or toric back surface, said variable front surface characterized by being geometrically and optically regular and continuous and having a pair of intersecting orthogonal principal planes.
U.S. Pat. No. 5,073,021 discloses a dual focal length ophthalmic lens formed from a birefringent material with its fast and slow axes perpendicular to the user's visual axis. The dual focal property arises due to the differing indices of refraction of the birefringent material for light polarized parallel to the fast and slow axes. Light emanating from far objects having one polarization and light emanating from near objects having the opposite polarization are both focused onto the user's retina. Depending upon which object is being viewed, an in-focus and a blurred image appear simultaneously on the user's retina. The ability of the user's eye/brain system to distinguish between the two images provides bifocal action from a single lens.
U.S. Pat. No. 5,223,862 discloses an ophthalmic lens embodying an organic plastic lens member having a refractive index of at least 1.56 and being the cured product of a monomeric formulation. The formulation contains a resin monomer base, a curing agent selected from aromatic anhydrides, aromatic diamines, thioamides and thioamines, and a refractive index enhancing additive selected from alkyl or aromatic diols or thiols and transition metal alkoxides. The organic plastic lens member may be an integral, monofocal lens, or a segment embedded in a cavity in the front, convex surface of an organic plastic, major lens member having a lesser refractive index. The latter may have a thin, inorganic glass lens member adhered to its front, convex surface to produce a glass-plastic, laminated, multifocal lens structure.
U.S. Pat. No. 5,408,281 discloses a multifocal ophthalmic lens with a spiral-like pattern on its surface in an area overlying the cornea of a wearer of the lens. The spiral-like pattern is capable of providing a plurality of different dioptric powers.
U.S. Pat. No. 5,690,953 discloses a soft hydrogel contact lens derived from a crosslinked polymer made by reacting a hydrophilic monomer with a cross linking amount of a polyfunctional compound containing a saccharide residue.
U.S. Pat. No. 5,702,440 discloses a multifocal ophthalmic lens having outer annular zones with vision correction powers less than a far vision correction power of the patient, is disclosed. These additional annular zones come into play, when the pupil size increases under dim lighting conditions, to thereby compensate for the near-vision powered annular zones. The net effect of the additional near vision annular zones and the additional annular zones having power less than the far vision correction power is to shift the best quality image from in front of the retina to an area on the retina of the eye
U.S. Pat. No. 6,158,862 discloses a multifocal ophthalmic lens having a dye or dyes that block the transmission of near UV and/or blue light.
U.S. Pat. No. 6,520,637 discloses an ophthalmic lens with a posterior surface and an anterior surface having a spherical central optical correction zone, an aspheric intermediate zone, and a peripheral zone.
U.S. Pat. No. 6,682,194 discloses a progressive multifocal ophthalmic lens having a far vision region, an intermediate vision region and a near vision region, a main meridian of progression passing through said three regions, and a power addition equal to a difference in mean sphere between a near vision region control point and a far vision region control point is provided.
U.S. Pat. No. 6,858,305 discloses an organic glass ophthalmic lens having an impact-resistant primer layer based on polyurethane latex and its manufacturing process.
U.S. Pat. No. 7,029,116 discloses an ophthalmic lens for nearsightedness, manufactured as a finished or semi-finished lens, lighter and thinner at the edges, with a wide visual field and cosmetically attractive, featuring a spherical centre and an aspherical periphery, both asymmetrical to the lens optical centre and varying in width.
U.S. Pat. No. 7,192,138 discloses an ophthalmic lens with an optical zone with a first corrective power range in a first region and a second corrective power range in an annular region surrounding the first optical zone.
U.S. Pat. No. 7,370,962 discloses an invention with a multifocal ophthalmic lens that both corrects for the wearer's refractive prescription and takes into account pupil size of a specific individual or of a population of individuals.
U.S. Pat. No. 7,404,638 discloses a method and apparatus for increasing the depth of focus of the human eye is comprised of a lens body, an optic in the lens body configured to produce light interference, and a pinhole-like optical aperture substantially in the center of the optic.
U.S. Pat. No. 7,441,894 discloses a trifocal ophthalmic lens that includes an optic having at least one optical surface, and a plurality of diffractive zones that are disposed on a portion of that surface about an optical axis of the optic.
U.S. Pat. No. 7,559,949 discloses an injectable intraocular lens formed in situ.
U.S. Pat. No. RE34, 251 discloses a multifocal, especially bifocal, intraocular, artificial ophthalmic lens of transparent material, whose optical lens portion is divided into near range and far range zones and, each of which is disposed on the optical lens portion with approximately equal surface proportions and symmetrically with the lens axis.
U.S. Pat. No. 5,033,839 discloses a unifocal ophthalmic lens with part-spherical concave and convex surfaces.
U.S. Pat. No. 5,106,180 discloses an ophthalmic lens with front and rear optical surfaces, a central optical axis substantially perpendicular to the lens and comprises a plurality of concentric, contiguous circular refractive bands provided on at least one of the front and rear optical surfaces.
U.S. Pat. No. 5,311,223 discloses an ophthalmic lens with a polymer composition composed of the reaction product of a hydrophilic monomer and an acyclic monomer is disclosed.
U.S. Pat. No. 5,517,260 discloses an ophthalmic lens including a first zone located in a central portion of the ophthalmic lens such that a central axis intersects the center of the first zone. The first zone having a spherical posterior surface for correcting distance vision. The ophthalmic lens further includes a second zone, positioned about the periphery of the first zone, and having a posterior surface of revolution defined by rotating a portion of a spiral curve about a central axis of the ophthalmic lens.
U.S. Pat. No. 5,699,142 discloses a multifocal ophthalmic lens including an apodization zone with echelettes having a smoothly reduced step height to shift the energy balance from the near image to the distant image and thus reduce the glare perceived when viewing a discrete, distant light source.
U.S. Pat. No. 6,145,987 discloses a multifocal ophthalmic lens with spherical aberration varying with the addition and the ametropia.
U.S. Pat. No. 6,196,685 discloses a method for fitting and designing an ophthalmic lens for a presbyope that yields improved visual acuity in general, and takes into account individual fitting characteristics.
U.S. Pat. No. 6,576,011 discloses a multifocal ophthalmic lens, having outer annular zones with vision correction powers less than a far vision correction power of the patient, is disclosed. These additional annular zones come into play, when the pupil size increases under dim lighting conditions.
U.S. Pat. No. 6,802,606 discloses a progressive multifocal ophthalmic lens pair in which the dominant eye lens incorporates more distance vision correction than does the lens for the non-dominant eye.
U.S. Pat. No. 7,004,585 discloses a lens with an anterior surface and an opposite posterior surface, wherein the anterior surface includes a vertical meridian, a horizontal meridian, and a central optical zone having at least a first optical zone for primary gaze, a second optical zone for down-gaze and an optical blending zone between the first and second optical zones.
U.S. Pat. No. 7,073,906 discloses a multifocal ophthalmic lens with a lens element having anterior and posterior surfaces with a central aspherical refractive zone disposed on one of the anterior and posterior surfaces; and a diffractive bifocal zone disposed outside of the aspherical refractive zone.
U.S. Pat. No. 7,210,780 discloses a method for determination by optimization of an ophthalmic lens for a wearer for whom a power addition has been prescribed.
U.S. Pat. No. 7,377,641 discloses a multifocal ophthalmic lens with one base focus and at least one additional focus, capable of reducing aberrations of the eye for at least one of the foci after its implantation, comprising the steps of: (i) characterizing at least one corneal surface as a mathematical model; (ii) calculating the resulting aberrations of said corneal surface(s) by employing said mathematical model; (iii) modeling the multifocal ophthalmic lens such that a wave front arriving from an optical system comprising said lens and said at least one corneal surface obtains reduced aberrations for at least one of the foci.
U.S. Pat. No. 7,427,134 discloses a multifocal ophthalmic lens with a complex surface having a prism reference point, a fitting cross, a progression meridian having a power addition greater than or equal to 1.5 diopters.
U.S. Pat. No. 7,455,404 discloses an ophthalmic lens for providing a plurality of foci has an optic comprising an anterior surface, a posterior surface, and an optical axis. The optic has a first region and a second region. The first region has a refractive optical power and comprises a multifocal phase plate for forming a first focus and a second focus.
Most IOLs in use today are composed of a thin optic (usually less than 1.0 mm at the thickest dimension) attached to haptics which center the IOL and keep it in place. Haptics apply radial or equatorial pressure to the suspensory ligament, compromising accommodation. It is an object of the present invention to provide an IOL that does not require haptics to stay centered in the eye capsule.
The current thin optic of IOL's available prior to the present application replace nature's 4.0-5.0 mm thick crystalline lens with a much flatter lens (on the order of 1 mm in anterior-posterior thickness). The flatness of the lens results in increases in the depth and volume of both the anterior chamber and the vitreous cavity. The vitreous body consequently has more space in which to move, and this instability has been associated with an increased incidence of retinal breaks and detachment. This problem is more significant if posterior vitreous detachment has not yet occurred.
Multifocal lenses do provide functional “pseudo accommodation.” However, this optical goal of multifocality is achieved at the expense of other important visual qualities: multifocal lenses create increased glare, and decreased contrast sensitivity and color discrimination. It is further an object of the present disclosure to provide an IOL having improved contrast sensitivity and color discrimination without undesirable glare.
Currently, the Crystalens IOL (Eyeonics, Inc., Aliso Viejo, Calif.) is the only FDA-approved accommodative IOL. This lens is similar to a traditional IOL in that it has an optic and haptics. However, unlike the traditional flat IOLs, the Crystalens has a movable haptic-optic junction that functions like a hinge and theoretically produces accommodation. Like traditional multipiece IOLs, of course, the Crystalens induces posterior capsular opacification, which requires post-operative Nd:YAG capsultomoties. This laser procedure creates an additional expense and potential complications, such as an increased risk of retinal detachments. Finally, such destruction of the posterior capsule may hinder the accommodative ability of this IOL. It is further an object of the present invention to provide an IOL which does not damage adjacent tissue.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is a need for a crystalline lens replacement with a close functional approximation of the healthy lens: a lens with varying dioptric power that is enclosed within the natural capsule. In this way, the ciliary muscles remain effective. There is a need for an IOL responsive to the ciliary muscle ring, such that when the IOL is implanted the zonular fibers surrounding the lens are not placed in a permanently relaxed state, allowing the lens to become more spherical than it would otherwise. The present invention provides a solution for these problems.
It is further an object of the present invention to replace the current technology of IOLs that imitate a presbyopic lens with a new IOL that imitates nature's accommodative lens. It is yet another object of the present invention to provide an injectable IOL to allow for a minimally-invasive limbal incision. Studies have shown that pressure exerted on the capsular bag reduces epithelial cell proliferation or migration at the area of contact. (Assia E I, Castaneda V E, Legler U F C, et al. Studies on cataract surgery and intraocular lenses at the Center for Intraocular Lens Research. Ophthalmol Clin North Am 1991; 4(2):251-266.) It is yet another object of the present invention to provide an optic that will not rub against the posterior capsular bag and will not create opacification of the posterior lens capsule.